1. Field of the Invention
The present invention relates generally to the electrolytic generation of a halogen, such as chlorine, for treating algae and bacteria within a water source, such as a swimming pool or spa. More particularly, the present invention relates to an improved system of controlling the production of the halogen through automatic adjustment in the production rate in response to changing demand.
2. Description of the Prior Art
The use of halogen, particularly chlorine, to treat algae and bacteria in water systems such as swimming pools and spas, is well known. A commonly used procedure involves the manual introduction of chemicals into the swimming pool. This method is too labor intensive in that it requires frequent testing of the water to determine chlorine demand in addition to the time that is required for the handling, storing and application of the chemicals. Safety issues are raised by the need for storage and handling of the potentially hazardous chemicals.
Other techniques involved electrolysis thereby avoiding the need for manual introduction of chemicals. One technique involving the use of a brine for generating chlorine gas and/or sodium hypochlorite is disclosed in U.S. Pat. No. 4,693,806 to Tucker and U.S. Pat. No. 5,037,519 to Wiscombe. An alternative is to use an electrolytic cell to produce a halogen, such as chlorine in the form of sodium hypochlorite, by passing water carrying the salt of the desired halogen, such as sodium chloride where chlorination is desired, through the cell. Such a system is disclosed in U.S. Pat. No. 4,100,052 to Stillman.
The electrolytic systems of the prior art typically utilize a fixed current power supply to generate chlorine with the amount of chlorine being produced controlled by varying the amount of time that the chlorination system is operating. The cycle time for the chlorination system will be set by a user of the system based on an estimation of the sanitization needs for the system. However, such a system will not respond to changes in the demand for sanitizer which may occur subsequently to the initial setting of the cycle time unless the cycle time is changed by a user of the system. The weakness in such systems is that under changing conditions, including temperature and pH of the water, the system will not be providing the appropriate level of chlorination at the time when it is needed. What is needed is a system which automatically responds to changing conditions to allow for instant modification of the rate of production of the sanitizer thereby more optimally matching sanitizer production with sanitizer demand. This will insure that sanitizing is adequate when the demand is high because of high water temperatures and resulting high bath load and there will not be overproduction when demand is low.
Therefore, it is an object of the present invention to provide a control system for the production of sanitizer within a water treatment system which automatically adjusts the rate of halogen production in response to changes in water conditions, including temperature or pH level.
It is a further object of the present invention to provide a sanitizing control system operable according to a preset program developed to respond to sanitizer consumption according to a programmed response parameter such as temperature or pH and with a feed back control loop to adjust sanitizer production when the programmed parameter differs from the predicted production requirements.